The making of the ZX Spectrum

The making of the ZX Spectrum

Turning it around

Sinclair demanded that the new hardware be turned from initial specifications to first production model in just five months. “It’s hard to believe how quickly we worked back then,” he said. “It was mainly thanks to having such an agile, enthusiastic, talented team.” Given scheduling constraints, the ZX Spectrum was shunted from prototype to manufacture with no room for testing or benchmarking. John Grant of ROM developer Nine Tiles remembered “people designing circuits on their bench, soldering in another resistor or logic gate to see what happened, and then, if it worked OK, sending it off so 10,000 could be manufactured. It wasn’t so much engineering as improvisation.”

Within Sinclair’s labs, components were overclocked as a matter of routine, new versions of BASIC were hastily tested on laboratory ROM chips which were still being tested themselves, and routines to control future peripherals were coded without finished hardware to hand. Many of the Spectrum’s most lovable quirks were the result of ingenious shortcuts and tricks implemented to keep costs down. For example, with colour information for 49,000 pixels contained in just 256 bytes, the hardware’s infamous ‘attribute clash’ was born, as pixels battled with each other to retain their own colours. Meanwhile, the hardware’s inability to load certain games after scores of attempts might have been due to the tape-handling routine being, in Grant’s words, “tested with around three casssette recorders before being sent off to be manufactured.”

With completion approaching, Sinclair’s new colour computer, internally referred to as the ZX82 throughout development, required a name. “We wanted something new that stressed the colour aspect of the machine,” Sinclair recalled. In the event, it was the girlfriend of Nigel Searle, Sinclair’s marketing director, who suggested the name ‘Spectrum’. The ‘ZX’ remained to reassure customers that they were buying into Sinclair’s next step in home computing – and to remind those in the know that the machine wasn’t too far removed from its older siblings, in order to forestall any possible disappointment.

Labour pains

Devising a new computer in five months was already some achievement, but then came the tricky part – the Spectrum’s launch seeing the company besieged by problems.

In February 1982, Nine Tiles’ Steven Vickers and Sinclair’s Richard Altwasser had departed to build their own Sinclair beater (the Jupiter Ace), leaving an unfinished ROM in early Spectrum models that required a plug-in circuit board (known as the ‘cockroach’) in order to function. Meanwhile, an early manufacturing problem for the machine resulted in ten-month delays in delivery, and a formal reprimand from the Advertising Standards Agency.

Once production stepped up, however, Sinclair saw sales reach a staggering 250,000 units per month. It was a British success story that encouraged Margaret Thatcher to present a machine to the Japanese premier as supposed proof of the UK’s technological superiority.

Of course, it soon became clear that the Spectrum was largely being bought in order to play games, which took Sinclair by surprise. “Initially, the target audience were people who wanted to learn about computers,” he said. “We realised that some of that would be done through games, with Spectrum owners typing in games programs printed in computer magazines.”

In fact, the flood of game software came as a direct result of Sinclair’s original dream. Teenage coders, tinkering with type-in programs and exploring the Spectrum’s foibles courtesy of Stephen Vickers’ excellent user manual and their own ingenuity, soon broke free of their bedrooms, and began creating, marketing and selling commercial software within months of the machine’s launch.

Those youngsters grew up to be the Peter Molyneuxs and Dave Perrys of today. And both they and the rest of the Spectrum-owning masses hold a special place in their hearts for the Spectrum and Sinclair himself. “We were working on some ideas for a very advanced games machine back in 1985,” the pioneer revealed to us in 2000. “I’d actually got the display working – one with which you could actually see a 3D world without glasses. I’d love to return to it. That would be very exciting, wouldn’t it?”

This is an edited version of an article that originally appeared in Edge’s Essential Hardware Guide 2000.